Metallfbg-ical pbocess



W. E. GREENAWALT METALLURGICAL PROCESS Filed Jan. 31 1925 Mme Oll FLHCOWcentmitor l l l A OXldlZed low Grade HlQhGIdE Tm u re Umd Or@ Ore Concentrate gr'gm@ M crpggaie LECETU Roashng Smeltmg Amd 501 Pumace Le 5 1 L hm'axV was" sforecnh Water eachmg JM W h ha Cu. Tank Wter omlgon- 50T; @generated SOiRe-ducer Y i AC1 n V... f- .Sol Lon 50 2 e e' 1 H25 Preclpacor.

C115 Ieltfzed CU Pfeflpl @.W Q Separahsr.

' Clueducef Eledm Coppermodes Co el' n .S "5 PEJXOL SGZReducer `Elec1crolyzed :501 O2 A l Solution o Wilwa ("1 Electrolyhc l Copper'remks F NO2 )I @1L RegeeYated/Scnd Sol. Foul Solution A( .D1 lute WashWater msg? Op 4 I A l Concenhatg (Hgglpg-Ilerrkraie Lean Co erSoluJmorl an steam, PP

Furnace Cu S eclprkzie centrate, but that the higher the grade of the high grade copper concentrate, the better the process can be operated. A ton of 60% copper concentrate would contain, approximately, copper, 1200 lbs., sulphur, 400 lbs.; impurities, 400 lbs.

The impurities may be assumed 'to 'be mostly iron, With its combined sulphur, silica and alumina, and combined oxygen.

lit' there is gold or silver in the ore, the high grade concentrate will contain the precious metals in about the same .proportion as it contains the copper from the orig'- inal ore. That is to say, ot the total precious metal content in the concentrate, 127.5% Will be in the one ton ot 60% copper concentrate, and 52.5% will he in the 9.0 tons of v7.5% copper concentrate.

'Having made the separation of the mineral from the ganaue and divided the mineral into a relatively small amount othiph grade concentrate and a relatively large amount ot low grade concentrate, the method of procedure is as follows, yret'ereucebeing' made to the accompanying' drawings, in which Fig. l is a diagrammatic flow sheet in plan ot' the process, and Fig. V'2 is a diagrammatic vflow sheet in section yot' that portion oi" the process 'which relates to the treatment 'of the high-grade concentrate and the production 'of the precipitant for the copper "from its solutions, and the application of the precipitant tothe copper-solutions.

'The low Agrade copper concentrate is roastedso as to convert asmueh as possible ot the copper into sulphate, which is solulole in Water, and which makes possible a high ere traction of the copper Lfrom the roasted material by Water and by acid leaching, and supplies the necessary acid for the process. rfhe 'roasted low grade concentrate is then loached ivith'a dilute acid solution, and the resulting copper solution, containing salts ot iron, is toen electrolyzed to deposit the copper, While at the same time acid and ferrie saltsare `regenerated. Vln order to avoid the harmful oiiects of the Jferrie iron in the electrolyte the sulphur dioxide from the roasting `furnace is applied to the lelectrolysed solution by Which means the ferrie iron, produced bythe electrolytic deposition ot'the copper, is maintained Within vfairly harmless limits.

rEhe copper solution :trom the leaching tank flows into the S02 reducer No. Land from the reducer'intothe electrolytic copper tanks llo. l. If desired, the solution may vhe'treated with 'CnS precipitate obtained trom fivaiste and foul1so lutions, in the 'CUS reducer, as Will be re-V -lierred to later.

The solution is 'flowed through the electrolytic copper tanlrs at a rate which expe,

rience has shown to be the most satisfactory 1n reterence to the formation of ferrie iron in the electrolyte in the deposition of the copper vtrom solution contamina salts fot iron. Usually theiamount ot liierric iron in the solution issuing from the electrolytic copper tanks should not exceed :about 0.25%, altho there is no detinite rule in this respect. The solution is-circulated in a sort ot closed circuit betiveen the SQ., reducer and the elec trlytic vcopper tanks No. l, until the desired amount of copper is removed from the solution, which, .in the case oii'a- 3.50% copper solution, would be yabout 1.5%, leavingv about '2.0% in the solution,,assuming two electrolytic and reduction circuits as shown in the drawing. Y

Aregulated stream o'tsolution-the regular :advance flow through Ythe lea-ching and electrolytic. circuit-is passed on 4to Vthe Ysecond clectrolytic unit, comprising the'SOgreducer No. Zandzthe elcctrolytic copper 'tanks No. 2, where more copper is deposited and moreacid and ferrie iron regenerated, Vand the cycle ot electrolysis and reduction 'is continued inthe second electrolytic unit until. the 'desired amount 'of 'copper has been removed, which, for the assumed solution, would be about 1.0% remo-ved, and about 1.09"@l remaining in .the solution. A portion of the'depleted copper solution-'the advance fioivwregenerated in acid, is ithen returned to the ore topassthrough another complete cycle of leaching.andlcopper deposition and acid regeneration` and this is continued indei'initely. Then one lot of ore or concen-V trate is treated, the solution is switched Vto a new charge. In this Way'thefcopper is extracted 'from the Ilow grade concentrate and converted into the electrolytic metal.

'llianiiiestl it this `cycle of solution Yand precipitation is continued, the solution Will becomccharged with iron and other impurities in a` short time soas "to malte 'its use undesirable, either as a solvent Vor as `an electrolyte. A certain'amount of'foul solution is therefore diverted from 'the leaching; and electrolytic circuit and Wasted, While an equivalent amount ot `Wash Water is added to the solution to make up the Aloss inthe regular operation o1 the process.

The copper in the foulsolution,'diverted from the leaching'an'delectrolytic circuit, is precipitated before '-.the solution is Wasted, preferably with hydrogen sulphide.

The Ageneration fot 'hydrogen sulphide r copper Yprecipitation purposes `has alw ys presenterv lsomething ot lproblem :in its commercial. application. vdrogen sulphide for commercial useris ordnarilyigen erated from ferrous sulphide, or iron matte, and acid, but this method is ifatheref-:pensive in copper ininingclistricts. lt involves the purcl ase or yspecial manufacture oit acid jtor this purpose. and thatshould be avoided il possible. rEhe `gemeral process, -as described, is usually self sustaining in acid; that is to Say, there is as much acid geuerued iu The, sleps ol rousliug', euchingg, reduction,` nud electrolysis7 if?, required to dissolve the Copper from lie ore Wiaihout rc-So tuig to speoiul :ubid u'imui'lfudure or purche v Such u @use it would he pzul'icillurly drehwle il the precipitaliou, of he copper, :froh-,1 the lenu nud foul 4 u'iom could he ufff uplished Willi u preciI-iiaut, .euch as hydrogen sulphide, produced from the ore mieli?, step iu lche recovery o'f lie Mapper.

According to he preeo arooui liehod hy ,f-Lejguru small uuuuili of high from u rrluli rely largo cemeulrule und lh ,A couceutf ie als: u source o' 'lo ,girecipilute he copper led iu leuclun w f or low grade oreR especia, und w je -heul eolutioue.

low i rouliod by rouw n, electrolysis, ue doaorihed. small 'f hi 1' l heated iu zu] eleffsric luruaee iu l M :is fi no' lericlu amount o1 iu :la rmfluciug arnesi here cop/oor sulphide i rl'o il; Colei Sulg'i'uuf auul co2 wel, A lugv is :nemesio-y for the coiuplee diseoiiaiutiou olf the copper uid Sulpluxr of the sulphide couceurul'e. Cuprous Suli'ihide 112.55, when heated to redneee in lhe inference or steiuu is hul ulig'hlly decomposed, hul- :it rho While heult easily oliuiuuble iu nu eloerio furuuffe iu u uom-oxidizing' uiuor here, the proue eulihide ie dissociated in r iufeeeuiio olf steam, with the result ghut lzu: e ruuuiilief-1 of lydrogeu und hx ogen sulphide uw geliller Vith sublime@ ulphur :ire evolved,

und the copper ie comple'oly tueur eleiuei i L redufwd to 'fhe metallic elfe. The reduction of rho oupifio sulphiden Cujl7 'to ihe cuiirous Sulplude,

teii'1p"i"-l;uro than that required :Foi the die eooiulzlou oli' th arduous si'alphide, hul; ue The ohi l is lo ohiuiu hyc'irogfeu ,f'ulphide :11d meuilliccopper 'l'roiu he high {g1-fue come trul'e7 u high touuieruture i'equilmd lo com plele the reduction.

rThe euprous; sulphide7 once heh` (fluire-,s only u roluiveijj eiuull um ,un diliouul heat to maintain i iiiou euiieraiuxio3 e, o friese Sho 500 dori'. C. to prevehi'; hydrogen sulphide.

lhilo ho regulation ol Oi lhe Cuprous sulphide in theeleorie mice iS quite easy, the ifegulullou of the relupeinture of the fuses iu the furnace is quite difficult. il? not mpofsfsihle lo got the murciluuui uiuouu ol? lig/*drogen Sulphide with u o u iuiuuuu :uuouul of free hydrogen und free Sulohur.

To meer l i. ,i all@ OW ,i where oufliliouis "L rodurllou of hydrogen Sul-- i l riollod :lud regule gruwel-luf he lun'fi'd io the uvdrofzjeu suluhido lifdrosfou und Sulphur 3() bei', efm'xziuii which muy h Wallin' ol" tl or oher uu from Sofroiu ueee 'Foul copper Wash Wzuere. fol'iou olE hjdrogl'eu Sulphidm elecric furnace or iu Vlhe Hub hon, preferably iu l 1 oil7 u' he used Wi'fh or Wilhou; slee-u1 und 'forms u Convenient Way of {siiliplyringr hydrogrei or a hydrogen Couniuiug Llui-,r :md u uiu 'ufr the reducing atmosphere desired Yfor rood operul'iugi; coudiioue, .T lk Celle J results @au he ohiuiued by utroduC-- r u hydrogen Containing' M elric furnace or into he rerfliilier. qpousive to produce iu j diimze` :zu-:l oil will ueiuxllv E ydrogeu Whl .h l. e lor my particular Coudiiou 'y he use.

e the Copper l, @Spireiuily fue circuitB Where il muy he siu'u, Y lo uuliou willi. he o l Sufi u vom floue uit@ used to reduce the ferrie iron produced ly the elcctrolytic deposition yof the copper to the Vferrous condition, While at the same time the copper ofthe precipitate is converted into the electrolytic metal, yas described more fully in my Patents No. 1,340,825. lday 18, 192 and No. 1357.495, Nov. 2, 1020.

The barren foul acid solution and Wash Waters may be Wasted, but if there is oxidized ore available for leaching, 'these foul and dilute acid solutions are 'advantageously used in leaching the copper from the oxidizcd ore. This oxidized ore Will frequently consist of the tailings from the preliminary concentration treatment for obtaining sulphide concentrates.

llVhcn the copper sulphide in the electric furnace has been reduced to metallic copper, it is drawn from the furnace and given any further desired treatment. lt is pre` ferred however to cast this impure copper into anodes and then place the copper anodes in the electrolytic copper tanks, 4using the leach copper solution as the electrolyte, and. thus the impure copper fromthe electric furnace n ay be converted into the pure electrolytic metal at very little additional expense. rlhe precious metals in the copper from the electric furnace are recovered from the insoluble residue in the electrolytic copper tanks. The electrolytic lcopper tanks .may therefore be used to'deposit copper from the leach solutions, to rcne the impure copper from the electric furnace, or both at the saine time in different tanks. This can .be done quite conveniently if suitable provision is made to talre care of the difference Vin the E. M. F. required for the deposit-ion of copper from insoluble anodes 'and from soluble anodes. The E. M. F. required to deposit the copper from leach solution, with lead anodes for example, will usually vary from 1.5 to 1.9 volts, While with soluble or copper anodesv for example, the E. M. F. Will usually vary 'from 0.2 to 0.3 volt, under the conditions assumed. The amount of copper depcsited, per ampere, will be about the .same in either case.

lt is desirable to have a high grade copper concentrate for treatment in the electric furnace for the reason that a large amountof impurity would interfere Wit-h getting good reacting conditions 'between the sulphur vapor and the hydrogen containing` fluid to form hydrogen sulphide. lf the copper concentrate contained a large amount of impurity, a procedure alzin to that of sinclung would have to be resorted to, and this would involve vigorous fiuxing and the separation and removal of the resulting slag'. Flr/'en with high grade concentrate some .s e; will form and Will have to be removed. it is largely to avoid this complication in connection with the production of hydrogen sulphide that the amount of impurity is neoafcs lless attendance, and if the concentrate ,is of very high grade, as preferred, theoperat-ion may proceed with a small amount of care or supervision. Another reason for preferring a high grade concentrate is that a small electric furnace, and hence a simple, equipment, is capable of a relatively large output of copper. An electric furnace vhavinga charge dimension of only 2 X 2 X2 feet, `or 3 x 3 X 1 foot, would take a charge ofa ton of concentrate, assuming the uf'eight of thereon*- centrate to vbeahout 250 lbs. per cubic foot. Each charge would producexabout 1200 lbs. of copper, under the assumed conditions of a'GOC/O copper concentrate.

ln case the ore is such that a high grade concentrate is not -obtainable direct from the ore either by gravity or flotation, as would be the case if the ore is largelypyritic and the copper in the form of chalcopyrite or bornite, with aconsequent large amount of gangue, it spreferredto smelt this medium grade ore or concentrate 'to slag off the iron, silica, `and other impurities, and then to .introduce `the resulting` high grade copper sulphide in molten vform into the electric vfurnace for the production of hydrogen `sulphide and metallic copper. In this also, only a very small smelting equipment Would be necessary for a relatively large output of copper from a concentrate containing` say, from 40% to 50% copper. Under such conditions there would not be any ditliculty in getting ya relatively pure copper sulphide for the electric furnace. Small smelting Vfurnaces are usually some: what impractical Aon ordinary low grade copper ores, but small units/are quite practical When smelting ya Well luiied high lor medium grade concentrate.

Theoretically, the sulphur combined with the copper `as C1125, inthe high grade concentrate Will combine Wit-h the copper ofthe precipitate Vas CUS; or, one. ton of copper will be produced in the electric furnace Ain the precipitation lof half a t0n vof copper from the leach solutions. From this it will be seen that a suitable Working relation can easily be established between the high grade and the low grade concentrate and betivecn the relative amounts of copper to be produced by leaching and by electric smelting.

lt Will also be noticed that by this method yof*precipitating copper from leach solutions, the precipitant, H25, is produced at a very small, or practically no entra expense, for it is believed that the electric smelt-ing of the relatively high grade concentrate, Where possible, offers certain advantages over treating the same material by any other method, either hydro or pyro metallurgically. v'Such an electric smelting process would not Ot ltselt' otl'er any advantage in the ordinary treatment et copper ore or concentrate for the reason that the treatment ot the lower inateriz l 'would still have to te dealt r, il the lower grade inaterial, in any case, elders the nies: dv prol-len, hy itselfj or in relation other steps.

in case sulphur in s li- Y, iftrin 'tor the l0 electric furnace is ecar'e, sulphur Japon o" eren sulphini' dion "i, ha*

into the electric u i tilier. @olie .may t hc-'i 'fui' charge in the electric lurnace, or glacer! in rectilier, if deiured, to the desired ig atmosphere. laryD it sulphur ii any terni is scarce, Gua o'' the precipitate rvy he used in turi ace, and the siilphur used "'ecipitation., irli'le Athe cop 3er or ate Vwould ,Je convert A t iferred, however, t i tor reducing Yl' since this oliers o coin. ert the cop- ML lill;

- reflucii jf la V Alli 1 if i D ci] ,a

ee cone deserih d lioweif'cr5 Y 1 we and a reiat en large amount casting the loW concen ,i or louV 40 l. l, process et treating copper ores coinig' ti the ore into a relatiif'elv sinall aniouut et hioh grade sulphide grade concentrate P- A l 9 40 ade concentrate, leaching the roasted low grade co centrate with suitable solvent tor tne coppcu heating the high grade sulphide concentrate to dissociate the combined copper and sulphur7 applying a hydrogen containing tluid to the resulting sulphur vapor to torni hydrogen sulphide.7 and precipitating copper troni the leach solution hydrogen sulphide, and precipitating copper lroin the leach solution troni the low grade concentrate with the hydrogen sulphide so obtained troni the high grade concentrate.

il process oic treating copper ores coinprisingj c -ncentrating the ore toreniove a on the copper as a relatively high t e sulphide concentrate, leachingthe low grade inatcrial troni which the high grade concentrate was separated with a suitahle solvent tor the copper, heating the high ade concentrate to dissociate the coinhined copper and sulphur, applying a lydrogen containnp liuid to the resulting sulphur if'apor to torni hydrogen sulphioe, and then precipitating' copoer troni the copper soluohtained :trol-n leaching the low grade erial with the hydrogen sulphide so oh- 'l 'troni the high grade concentrate.

la il process ot treating copper ore coinprising, concentrating the ore to remove a portion the copper as a relatively high grade concentrate5 leaching low grade copper hearing inaterial with an acid solution to Vact the copper? elcctrolyzing the resulting copper soli `on to depos'* the copper and AGL le :.'egenerate acid, returning the regenerated acid solution to the ore and repeatii `the cycle ot leaching and electrolysis unlAIL the solution becomes fouled with impurities, heating the high grty de sulphide concentrate to dissociate the combined copper and eulphur, applying a hydrogen col'itaining l'luid to the resulting sulphur yapor to torni hydrogen sulphide, and then precipitating the copper rein the :toul leach solution troni the loW grade copper hearing niaterial with said hydrogen sulphide.

5. i process ot treating copper ores coinprising7 concentrating the ore to reinore a portion ot the copper as a relatively high grade sulphide concentrate7 leaching leu7 grade copper bearing niaterial with an acid solution to extract the copper and regenerate acid and then returning the acid solution to the ore or low grade copper hearing mats rial, heat-ing the high grade sulphide concentrate to dissociate the combined copper and sulphur, applying a hydrogen containing liuid to the resulting sulphur Vapor to forni hydrogen sulphide, applying the hydrogen sulphh` e so produced to the 1foul elec trolyzed solution resulting trein caching the low grade material, casting the resulting copper troni the high grade concentrate into suitable anodes7 and then refining said anodes in the copper electrolyte in the leaching and 1electrolytic circuit.

il process et treating copper ores coin prising, concentrating the ore into a relatively sinall amount ot high grade sulphide concentrate and a relatively large ainount of low grade concentrate, roasting the low grade concentrate, leaching the roasted low grade concentrate with an acid solution to extract the copper, electrolyzing the result;- ing copper solution to deposit the copper and regenerate acid, returning` the regenerated acid solution to the roasted low grade concentrate and repeating the cycle until the copper in the loiv grade concentrate is suliciently extracted, heating the high grade concentrate to dissociate the combined cop per and sulphur, casting' the resulting impure copper from the high grade concentrate into anodes, and relining said anodes in the electrolyte or solution obtained from leaching' the low grade concentrate.

7. A process ot treating copper` ores coinprising, concentrating the ore to remove a portion of the copper' as av sulphide concentrate, leaching low grade copper bearing material with an acid solution to extract the copper,y smelting the sulphide concentrate to remove impurities and to obtain a high grade copper' sulphide, heating the copper sulphide in an electric furnace in a reducing atmosphere to dissociate the combined copper and sulphur, applying a hydrogen containing iiuid to the resulting sulphur vapor to form hydrogen sulphide, and then precipitating copper from the leach copper solution With said hydrogen sulphide.

8. A metallurgical process comprising, concentrating ores oll metals to remove a relatively high grade sulphide concentrate, leaching' the resulting low grade material With a suitable solvent to extract the metals, heating the high grade concentrate in an electric furnace in a reducing atmosphere to drive oil the sulphur, passing the resulting sulphur vapor together With a hydrogen containing gas through a rectifier or cham-- ber maintained at the desired temperature to combine the sulphur and the hydrogen to iorm hydrogenl sulphide, and then precipitating metals from the leach solution with said hydrogen sulphide.

9. A metallurgical process comprising, concentrating copper ore to remove a relatively high grade sulphide concentrate, leaching the resulting low grade material With a suitable solvent to extract the copper, heating the sulphide concentrate in an electric furnace to dissociate the combined copper and sulphur, u'applying a hydrogen containing fluid to the resulting sulphur vapor in the presence et acatalytic agent to combine the sulphur and hydrogen to orm hydrogen sulphide, and then precipitating copper from the leach solutions with said hydrogen sulphide.

l0. i metallurgical 'process comprising, co icentrating ores ot metals to remove a high grade sulphide concentrate, leaching relatively low grade ores of the metals With a suitable solvent -lf'or the metals, heating the high grade sulphide concentrate in` an lelectric furnace to dissociate the sulphur, and

then as a separate step combining the dissociated sulphur With hydrogen in the presence ot a substance capable of promoting the reaction between the sulphur vapor and a hydrogen containing fluid to produce hydrogen sulphide, and then precipitating metals from the leach solution with said hydrogen sulphide.

l1. ln the production ot hydrogen sulphide for precipitating metals from leach solutions the steps comprising, heating a sulphide concentrate in a. reducing atmosphere to dissociate t-he sulphur, then as a separate step from said heating and' dissociation combining the resulting sulphur vapor' with hydrogen in the presence of a catalytic agent heated to the reacting temperature between sulphur and hydrogen 'to form hydrogen sulphide. f

l2. A metallurgical process comprising, leaching low grade ores ot metals with a suitable solvent tor the metals, heatinga sulphide concentrate in a reducing atmosphere in an electric furnace to dissociate the copper and the sulphur, then as a separate step trom. said heating and dissociation combining the resulting sulphur vapor with hydrogen to form hydrogen sulphide in theY presence of a substance capable of promoting the reaction While subjecting saidv substance to the action ot an electric current, and precipitating metals from the leach solution with the hydrogen sulphide so formed.

13. i metallurgical process comprising,V

leaching lov? grade ores oi" metals with a suitable solvent for the metals, treating a sulphur containing substance in a reducing atmosphere to form sulphur vapor, then as a separate step from said formation' of sulphur vapor combining the sulphur vapor with hydrogen to form hydrogen sulphide by heating' the sulphur vapor and hydrogen. containing fluid to a reacting temperature in the presence ot a catalytic agent capable of promoting thev reactionT and then precipitating metals from the leach solutions With the hydrogen sulphide so termed..

lil. A process ot' treating copper ores comprising, concentrating the ore into a relatively small amount ot high grade sulphide concentrate' and relatively large amount of loiv grade concentrate, roasting the loW grade concentrate, leaching the roasted low grade concentrate with a dilute acid solution to extract the copper, electrolyzing the resulting copper solution to deposit the copper and regenerate acid, returning the regenerated acid solution to the ore and repeating the cycle ot leaching and electrolysis until the copper in the roasted concentrate is su'lliciently extracted, 'heating the high grade sulphide concentrate to dissociate the combined copper and sulphur, combining the resulting sulphur vapor With hydrogen to form hydrogen sulphide, precipitating the lSO CIU

Leoejo copper from the foul electrolyzed solutions with hydrogen sulphide, applying thc CuS prooi iizie lo the eleeeroly'e, and applying the impure copper iroiii 4he high grade cohcentrzice to ldie electrolye es oiiodes to convert it iiilo the eleccrolytic metal.

l5. A procese or treating copper ores conv prieiiig7 coucentrziiiig the ore iiio :i relotivcly Smell amori il; oi? high grode sulphide concentrate, leechiiiag zi low `grade copper ore u'iih i cuite-,hie solvent "ao eiirect hc Copper. hcaiiig lle lifgh grade sulphide colicei U e, d'ssofioe che con )ined copper and sulphur, peesiug Jdie resiuiiinj Sulphur Vapor and o hwl ou containing fluid through JJe i liceo )if :au iiicoudeeceiit @TQS Gilliler willi ou eci'fl phuif conto, o reducing' i phur of the 'then paesini; drogen couioiu" stico@ oi e muse poScd of p' iii i 1 rrlliilh' ifliid i of ir if i... QGilQCilLl d per o 'u elocric i f lo com- ;iformetioo of he -i sulphide comhiiied sulphur vapo" and lijfii precipiiA ig copper from the i 'ions Wi h :foi-d hydrogen sulphide. pr of reeiiig milled sulphide l o c ou( oxide ores olf copper com) 13mg, per lling he pulverized i re hy gravity or {lotoi 'lou coiieciitrelion ihlo o high gli-ode sulpliido coicci tr `te5 o low ide eoiiccliirirce, l mi oxidized 'Ceiling1 roeefiiig `the low 1c conccnl/irate5 leaching he roasted low nitrate Wiinh o dilute acid solution sulting copper solution lo iepoei'c the copper oud regenerate zuid, r iiiiiiiilgy llhe regenerated 'e ion 'die r @Sled coiiceurelo a d repeating jdie cycle whereby excess' acid ie produced, leechiiio Jche oxidized failing with the excess acid l duccd hy ithe electrolysis oil the lerici ifroiii the l i il; high grade sulphide coiiceiitree to dies/eilte@ the copi er und A applying; o hydro ,ii contriniiifr i'iui-d lio ihe resulting pl forni hyd ofjgeii sull lining co"IV leen me h l :ii l oiii hy( ro i sulphide,

i de

. ifi Lfoeess of treating mixed sulphi oxide ores oicopper comprising, ee in the pulver-ized ore hy gravity l 'lou coiicehtroi'ion iiio :i hi j coucciuirzie, o low grade cori/eenL phiile7 (lud treo he resulting copper l' 'Y 20.. il procese of n 3cr orco coruprisiuggg, coiiceiitioiiii,; lo o relatively Smell amount of high grml` euhphide cohccn'role and o rcioively le (4e `iiouiit of grade coiiceiilrete, leo.chiugg` the ced louT grade concentrate with on acid solution, electroljmiiigjg lahc resulting); copper eolutiou coiloiuiiip; eolie of .iron to deposit` the copper zuid regeiieraie acid and ferrie iron oud returning `the clectroiyed solution to Jdie roasted coiiceiimzite7 applying the sulphur dioxide from roasting' the low grr de couceiil'rof'e to die electrolyte as o reducing; agent for the Yferrie iroii formed hy Jdie electrolyeis7 heating 'the high grade sulphide concentrate to diesociae *che copper and Sul* phur, combining the dissociated Sulphur with hydrogen to forro hydrogen sulphide7 and using said hydrogen sulphide of; a precipitating agent for copper in the 'foul und leon leach solutions obtained in treating the low guide concentrate.

21. A metallurgical process comprising7 concentrating copper ore to obtain e relloW grade coiiceuirnl'ea roast'iiig tie lou7 l lO atively high grade copper sulphide concentrate, leaching copper ore with a suitable solvent toextract the copper, heatingvk the sulphide copper concentrate in an electric furnace todissociate the combined copper and sulphur, combining the resulting sulphur vapor With a gaseous element', and applying the resultino` sulphur compound to the leach copper solution.

22.V A inetf'allurgicalv process comprising, concentrating" copper oreI into a relatively high grade sulphide concentrate anda rela:- tively low grade residue, leaching the relatively low grade-residue with an acid solution' to extract the copper, electrolyzing the resulting copper solution to deposit the copper'and regenerate acid, returning' the regenerated acid solution tothe low gradeL residue andy repeating the cycle, heating the high grade sulphide copper concentrate in an electric furnace to dissociate the combined copper and sulphur, combining the resulting sulphur vapor with a gaseous elenientfto torni a reducinggas, and applying the redi: ing gas tothe-copper leach solution as aiedncing' or a precipitation agent.

A process comprising concentratingy copper ore into a loW grade and a liiglr grade concentrate, roasting the low grade concentrate, leaching the roasted lour gradeV concentrate With an acid solution to extract the copper, electrolyzing the resulting copper solution to deposit the copper and regencrat acid and returning the regenerated acid solution to the roasted low grade concentrate, fusing the unroasted high grade-concentate to eliminate sulphur andc slag oi'i'liinpurities,

dissolving the copper from the resulting Jfused copper product in the solution olotained from leaching the roasted; low grade concentrate, and depositing the dissolved copper as the electrolytic metal.

24. A metallurgical process comprising, concentrating copper ore into a high grade and a low grade concentrate, roasting the lov1 grade concentrate, leaching` the roasted low grade concentrate With` a dilute acid solution to4 extract thel copper, eleeti'olyzing the resulting copper solution to deposit the copper, fusing the high grade concentrate to still further concentrate it by eliminating sulphur and slagging oit i1npuritiescasting the resulting fused concentrated copper product into anodes, and reiining said anodes in the solution obtained from leaching the roasted loW grade copper concentrate as an electrolyte. l

25. A metallurgical process comprising, concentrating copper ore into a high grade and a low grade concentrate, roasting the low grade concentrate, leaching the roasted low grade concentrate with a dilute acidsolution to. extract the copper, electrolyzing the resulting copper solution to deposit the copper, fusing the high grade copper concentrate in an electric furnace in a non-oxidizing atmosphere to still further concentrate it by elin'iinating sulphur and' slagging off impurities,. castingthe resulting fused concentrated copper product into anodes, rehning said anodes in the copper solution obtained troni leaching the roastedl low grade concentrate as an electrolyte, combining the sulphur vapor from' the electric furnace with hydrogen.- to form hydrogen sulphide, and applying saidV hydrogen sulphide to lean` and foul leach copper solutions to precipitate the copper therefrom.-

VVILLIAM E. GREENAlVA-LT. 

